In some high density plasma chemical vapor deposition (HDP-CVD) processing chambers, a baffle may be used for gas injection and distribution during substrate processing. Baffles for HDP-CVD chambers have typically been constructed from aluminum oxide (Al2O3). However, with the use of the high RF power HDP-CVD processes to access smaller device nodes, elevated temperatures result in the reaction of the aluminum oxide with process gases, for example, nitrogen trifluoride (NF3), which can be used as a cleaning gas for HDP-CVD chambers. Thus, owing to improved thermal conductivity, among other factors, aluminum oxide baffles have been replaced with aluminum nitride (AlN) baffles.
Unfortunately, although aluminum nitride baffles have some favorable properties, other problems remain. For example, aluminum nitride baffles are commonly manufactured by a sintering process that includes metal oxide binding agents. The metal oxide binding agents contribute to the high thermal conductivity of the sintered aluminum nitride. However, these binding agents, present on the surface of the baffle after sintering, undesirably interfere with the adhesion of a silicon oxide (SiO2) layer during seasoning of the baffle prior to substrate processing. Seasoning, for instance, can prevent contamination of a substrate by materials of the baffle, and can protect the baffle from reactive gases during processing or cleaning. However, the poorly adhered silicon oxide seasoning layer can flake off the surface of the baffle, thus contaminating a substrate being processed, and may also leave the baffle susceptible to damage from reactive gases supplied during substrate processing or chamber cleaning. Although this problem may be eliminated by not using metal oxide binding agents, such an approach would undesirably reduce the thermal conductivity of the baffle.
Thus, there is a need in the art for improved aluminum nitride baffles and methods for manufacturing the same.